Field of the Disclosure
The teachings in accordance with the exemplary embodiments of this present disclosure generally relate to an apparatus for warning of exceeding speed limit in railway vehicles, and more particularly to an apparatus for warning of exceeding speed limit in railway vehicles configured to warn in advance to a driver or a supervisor lest a train exceed an operation limit speed in an automatic train operation system.
Discussion of the Related Art
This section provides background information related to the present disclosure which is not necessarily prior art. The railway vehicle(s) may be interchangeably used with train(s).
In general, an object of automatic train operation (running) is to enable a train to run at a predetermined target speed at each operation section, and to effectively and safely stop at a designated position at a train station.
In case of a CBTC (Communication-Based Train Control) operated by radio communication, protection of train is performed by ATP (Automatic Train Protection) system, and operations such as train speed control and the like are performed by ATO (Automatic Train Operation) system.
The ATP system sets up an ATP speed profile or ATP speed limit in consideration of various factors including train speed limit at each section, stop position in response to movement authority and safety brake model. The speed limit is transmitted to the ATO system, where the ATO system generates an ATO speed profile in consideration of various factors such as ride comfort or adhesion coefficient, lest the train exceed the limit during train operation.
Furthermore, the ATO system includes an ATO speed following controller configured to control deceleration/acceleration of a train in order to follow the ATO speed profile, and the ATO speed profile and a current train speed are compared to input propulsion and braking command to a train propulsion system and braking system, whereby the train is operated to follow a predetermined ATO speed profile. That is, the ATO system enables a train to operate in response to a train operation strategy within a scope not exceeding a speed limit.
If a train approaches a speed limit at a given moment, the ATP system transmits a warning signal to a driver or a supervisor. Furthermore, if a train exceeds a speed limit while there is no particular measure by the driver or a supervisor, an emergency braking command is provided to the train, and function to protect a train is performed to allow the train to stop in response to the emergency braking, whereby the train is enabled to safely operate.
Furthermore, in order to directly react to the warning signal transmitted to the driver or the supervisor, the ATP system may activate an on-board braking system to decelerate the train speed when the warning signal is received. In this case, a speed limit value is set to directly warn to the ATP system. That is, the ATP system sets a speed limit curve for activating the emergency braking and as the same time, generates a warning signal, and sets a speed limit curve line for activating an on-board braking system.
Meantime, the ATP system conservatively considers a speed safety margin in setting the speed limit for warning in order to safely protect the train. Thus, even if there is a sufficient allowance in operation, the ATP system provides a warning signal to the driver or the supervisor regarding over-speed to result in limiting the train operation speed. For example, assuming that the ATP system sets an emergency braking ATP speed limit value at 90 km/h, the ATP system warns to the driver if the train speed exceeds 85 km/h, and activates an emergency braking when the train speed exceeds 90 km/h.
FIG. 1 is a graph illustrating control of a train speed according to prior art.
Referring to FIG. 1, T1 is a current time, Tw is a time when a train speed (1-1) exceeds an ATP speed limit for warning (1-5), and Te is a time when the train speed (1-1) exceeds an ATP speed limit for emergency braking (1-2).
In general, the ATP speed limit is provided in two types in setting speed limit curves, that is, one is the ATP speed limit for warning (1-5) and the other is the ATP speed limit for emergency braking (1-2), and when a train exceeds the ATP speed limit for warning, the ATP system transmits warning to a driver or a supervisor. However, when the train speed exceeds the ATP speed limit for emergency braking, because no subsequent follow-up action is made in response to the transmitted warning, the train is stopped by activating an emergency braking.
That is, if the train is running at the train speed (1-1) as illustrated in FIG. 1, the ATP system transmits a warning signal to the driver or the supervisor at Tw, and transmits an emergency braking command to the train at Te, whereby the train is stopped by the emergency braking.
Thus, in the system like the above, it is general that a safety margin of a predetermined value is provided to an ATP speed limit for emergency braking to set a speed limit for warning, where the ATP speed limit for warning is generally set lower by a predetermined value than the ATP speed limit for emergency braking
Furthermore, because of adoption of a conservative viewpoint in operation method and provision of greater margin thereto to prevent the emergency braking from happening during train operation, the train speed is reduced by providing a warning to the driver or the supervisor according to the conservative viewpoint in operation method, even though a train can run at a faster speed while not exceeding the emergency speed limit during a sufficient time.
Because a scheduled speed which is a moving time between train stations is determined in train operation based on size of margin and how conservatively a train is operated, a train running frequency at a relevant line is resultantly reduced to disadvantageously decrease the operational efficiency in terms of economic viewpoint.
Hence, a method is required capable of more efficiently handling a warning speed limit while a train safety is guaranteed.